[Merged by Bors] - Bump stacks and demos to 23.4 and parameterize them

[sbernauer]

Description

To test run (from feature branch) stackablectl --additional-stacks-file stacks/stacks-v2.yaml --additional-demos-file demos/demos-v2.yaml demo list

Criteria

• [x] Bump all product versions
• [x] Bump all helm-charts, such as postgres, redis, minio etc.
• [x] Parametrize stacks (and demos), so that at least public credentials (e.g. admin) can be changed to secure values

Review Checklist

• [x] Code contains useful comments
• [x] (Integration-)Test cases added (or not applicable)
• [x] Documentation added (or not applicable)
• [x] Changelog updated (or not applicable)
• [x] Cargo.toml only contains references to git tags (not specific commits or branches)

Once the review is done, comment bors r+ (or bors merge) to merge. Further information

[sbernauer]

bors r+

[bors[bot]]

Pull request successfully merged into main.

Build succeeded:

• Run Rustfmt